Diaphragm chucks are well known in the art and have been extensively used. They have, however, been subject to a serious limitation. Due to the nature of the chuck, as the speed of the chuck increases, the resulting centrifugal force acts to bias the jaws of the chuck to open. As a result, this type of chuck has been limited to relatively slow speeds to avoid build up of centrifugal force. It has been attempted to overcome this problem by making the diaphragm stiffer, increasing resistance to centrifugal forces. This, however, materially increases the weight of the chuck and requires much higher forces to overcome the diaphragm's resistance to open the chuck. The degree of improvement that can be accomplished by this technique is quite limited.
Despite these shortcomings, diaphragm chucks have been used frequently because they have the desirable characteristics of being relatively compact and of simple construction and, thus, relatively inexpensive.